PSI - Issue 11

Gabriela Lotufo Oliveira et al. / Procedia Structural Integrity 11 (2018) 242–249 Gabriela Lotufo Oliveira, Fabiana Lopes de Oliveira, Sérgio Brazolin / Structural Integrity Procedia 00 (2018) 000–000

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Fig. 3. Australian´s climate-index map, based on Scheffer´s index.

Comparing the three maps, it´s possible to see that in all studied countries, there are regions with climate conditions most favorable for decay to occur. However, as pointed by Martins et al. (2003), in all Brazilian regions, with just a few exceptions, there are the most conductive conditions to decay, since the index values are higher than 70 in most of the country area. Therefore, it can be concluded that from the three countries above, Brazil is the one with the highest potential for decay to occur. 3. Wood preservation The modern age of wood preservation started with the patenting of Creosote, as a wood preserver, and with advent of the full cell process for delivering that product into wood, back at the 1830s. Creosote was for a long time the most effective of all treatment systems available (Morrell, 2006). This oil-based preservative was mainly used for poles, crossties and posts, not recommended for buildings, considering its odor and oil exudation. In the 1930s, two important new systems were developed, Pentachlorophenol and CCA (Chromate Copper Arsenate). Pentachlorophenol was an oil-based material that emerged as a substitute to Creosote and CCA was a mixture of copper, chromium and arsenic - metals dissolved in water. Cooper is a highly effective fungicide and arsenic is an insecticide; chromium reacts with both promoting their fixation in the wood, avoiding their leaching to the environment. Until the 2000s, CCA was the most important chemical used to protect wood (Morrell, 2006). However, in the USA, around the beginning of the 2000s, there was a growing concern about the health effects associated with exposure to CCA preserved wood due to arsenate. The greatest concern was the risk of developing some types of cancer later in life (West, 2004). Therefore, on December 31, 2003, the Environmental Protection Agency (EPA) and the lumber industry of the United States decided to withdraw the registration of CCA for residential use (Morrell, 2006), such as playgrounds, decks and picnic tables, voluntary; thus, avoiding direct contact with people. Nevertheless, CCA-treated wood is still used for commercial and industrial purposes. In this scenario, other chemicals were developed to replace arsenate-based products. One of them is a mixture of copper, chromium and boron (CCB), diluted in water, which has been first commercialized in Germany at the beginning of the 1960s (Oliveira et al., 1986). In this chemical, boron is effective against insects, functioning as an arsenate substitute. In Brazil, CCB is frequently used for construction, although there is no governmental restriction to use CCA. To regulate the use of those chemicals, in most countries, there are wood treatment specifications. In the USA, the American Wood Protection Association (AWPA), founded in 1904, standardizes treatment processes and develops standards for wood preservatives and treatments for different degrees of risk of decay, which are divided in use categories (Morrell, 2006), considering the biological use conditions and the presence of xylophagous organisms (AWPA, 2017). As shown in Table 1, the first category (UC1) represents the lowest risk and the last category (UC5), the highest.